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Outdoor Photogrammetry: Issues and Questions

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#1 kagidusko



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Posted 20 November 2017 - 08:00 PM

Hello all,


I am currently trying to test the use of CRP for outdoor forensic scenarios in common SE U.S. environments like oak hammocks and pine flat-woods. I am using plastic teaching skeletons to represent human remains scatters of varying types. I have a couple issues I was hoping folks could weigh in about and also wanted to see if anyone had any good articles/books I should maybe dive more into that might help on this particular subject:


  • It is incredibly hard to walk in between the scatter without moving anything. Would it be worthwhile to set up a tall tripod/monopod (8ft or so) and shoot around the scene? I feel as though I'd be losing too much detail, and accuracy of the scene is key. Currently I am shooting about 5.5-6ft off the ground, eye-level height for me for the most part.
  • I am shooting with the aperture priority setting, iso 100, in RAW format. Using a Canon Rebel T5i and shooting at about 23-24mm, depending on what I set it too before taking auto focus off. I have also completed some test runs using the CHI scale bars. I'm still getting a little blur on details, so much so that I can't really detect marker points on about half the images at times. Should I be shooting differently?
  • I'm often having to shoot in weird patterns/positions as we're trying to make the scenes as real as possible. Am I tanking accuracy by moving all over the place?
  • When processing, for the widest scatters, I have had to "detect markers" within the program prior to the initial photo alignment. Does this drastically alter error to do so before a sparse point cloud is generated?
  • I'm finding that the models are getting super complex with all of the leaf and pine needle litter. Is there any way to control for that without loosing accuracy of info on "bones"? 
  • I am getting some wavy-ness along some of the bones, or it appears that they are in a haze. Any idea what might account for this and how I can correct it?

Thanks in advance for any insight!




#2 leszekp


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Posted 20 November 2017 - 08:17 PM

You might try shooting at a slightly higher ISO (up to 400); you'll get faster shutter speeds to reduce the blur, and the added noise is likely to be small. You might also try processing the dense cloud at UltraHigh to get better resolution for your models. Using a camera pole can get you higher camera elevations, for more angles. With a faster shutter, you can try holding the camera pole obliquely to get good angles above the scene without disturbing the area.

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#3 kagidusko



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Posted 27 November 2017 - 09:31 PM

Here's a medium run, decimated version of what I'm trying to do, if it helps to see. Am I just not going to have a lot of definition because of the complexity of all the pine needles? Anything I could have done better besides the advice above?




Pass: thesis

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